It\u2019s an interesting object astronomically, showing subtle atmospheric markings through the eyepiece, as well as displaying striking changes in phase and apparent diameter.<\/p>\n
- 6 ways to observe Venus<\/strong><\/em><\/a><\/li>\n<\/ul>
![\"""\"]( "\\"\"\"\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>You can produce diffraction spikes by stopping down a camera lens, using Venus as the bright light source. As shown here with both the Moon and Venus, the spike quality can vary between lenses. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n Venus is interesting for another reason too. Being so intensely bright \u2013 the brightest of all the planets and often referred to as the morning or evening star<\/a> \u2013 it\u2019s essentially a point source at low magnification, and ideal for demonstrating experiments with light.<\/p>\n
When placed in a dark sky, it\u2019s possible to experience Venus\u2019s light casting a shadow \u2013 okay, it\u2019s a dim shadow, but it\u2019s one that can be photographed.<\/p>\n
Being very close to a point light source, the shadow cast is really sharp and well-defined too.<\/p>\n
You can also capture diffraction spikes when photographing Venus, and image the rainbow-like effect of dispersion.<\/p>\n
Here are three ways of photographing Venus that you may not have tried before. Give at least one of them a go!<\/p>\n
You\u2019ll need a DSLR camera with lens, a tripod or, preferably, a tracking mount<\/p>\n
3 astrophotography experiments with Venus<\/strong><\/h2>\n
Photograph a shadow cast by Venus<\/strong><\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>A view out of the window with the shadow-casting Venus symbol attached to the glass. Venus\u2019s light had to pass through tree branches on the way. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n To record the elusive effect of a shadow cast by Venus\u2019s light, you\u2019ll need to be somewhere where there are no other light sources. Even a bright sky can interfere.<\/p>\n
A west or northwest-facing window is ideal, as long as you can turn all of the lights off.<\/p>\n
If you can\u2019t do this, use a large cardboard box with the opening pointed at Venus.<\/p>\n
Either way, you\u2019ll need a screen on which the shadow will be cast. This can be as simple as a light-coloured wall or several large white sheets of paper.<\/p>\n
You\u2019ll need a shadow-casting subject as well. This can be a shape cut from card pasted on a window or suspended in front of the box.<\/p>\n
Then it\u2019s simply a case of pointing a camera at the screen, focusing and taking your shot.<\/p>\n
A high ISO is recommended to keep the exposure times short; take too long and the razor-sharp edge of the shadow will blur as Venus moves relative to the horizon.<\/p>\n
How to do it<\/strong><\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>As Venus is essentially a point source, the resulting shadows all appear sharp when cast on the wall. (Camera settings: ISO 12,800, 20\u201d exposure at f\/5.6). Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n A west or northwest-facing window is ideal for capturing the shadow of Venus.<\/span><\/p>\n
In a darkened room, attach a shape to a window pane to act as a shadow caster \u2013 in this case a cardboard cutout of the symbol of Venus.<\/span><\/p>\n
The line from Venus through the target should ideally end up on a flat \u2018screen\u2019 wall.<\/span><\/p>\n
Despite Venus being such a brilliant planet, its shadow is still dim and will require an extended exposure.<\/span><\/p>\n
A mid to high ISO and low f\/ number are essential. In our example above, there was a tree between Venus and our shadow target.<\/span><\/p>\n
An exposure of 20 seconds was required. If exposures are too long, the shadow edges will blur. <\/span><\/p>\n
Capture a Venus rainbow<\/b><\/span><\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>A rainbow effect caused by capturing the dispersion of Venus\u2019s light. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n Another interesting effect to see with Venus is something which is a nuisance for planetary imaging: atmospheric dispersion (hence the existence of atmospheric dispersion correctors<\/a>)<\/p>\n
This is caused by the light-dispersion quality of our atmosphere. Essentially, the atmosphere acts like a giant prism, refracting light that passes through it.<\/p>\n
The thicker the atmospheric layer, the more bending that takes place. In other words, the bending is greater at lower altitude.<\/p>\n
As white light passes through the atmosphere, different wavelengths of light get refracted by different amounts, resulting in an object\u2019s light being spread into a small spectrum.<\/p>\n
The effect is noticeable around the edge of the Moon, but the brilliance of Venus means it\u2019s easier to stay with the effect at lower altitude.<\/p>\n
Using a long-focal-length lens or telescope, it\u2019s possible to see Venus completely smear into a small rainbow of colour.<\/p>\n
How to do it<\/strong><\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Dispersion can also be achieved when photographing Mercury, as shown here. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n The sequence above, imaged through a low-power telescope as Venus was setting, shows the effects of atmospheric dispersion.<\/span><\/p>\n
Venus\u2019s light is spread into a spectrum, varying in intensity according to atmospheric stability (seeing<\/a>).<\/span><\/p>\n
Just before setting, the green edge of Venus detached, creating a Venusian \u2018green flash\u2019<\/a>.<\/span><\/p>\n
Although dispersion is easier to record with bright Venus, it\u2019s not the only object to show it.<\/span><\/p>\n
Mercury is another target that will show dispersion well. Its proximity to the Sun means you\u2019ll typically need to record its colour spread against twilit skies, as shown here. <\/span><\/p>\n
Capture Venus diffraction spikes<\/strong><\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Cotton vains across the front of your scope will help you generate the diffraction spike effect when photographing Venus. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n Finally, the planet\u2019s brilliance and point-source nature make it ideal for experimenting with diffraction.<\/span><\/p>\n
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